Cooling and retaining pin for an apparatus for cooling and handling preforms made of plastic material

Abstract

A cooling and retaining pin ( 1 ) for cooling, by air blowing, and retaining, by air suction, a plastic preform, the pin comprising a body ( 2 ), defining a longitudinal axis and having a first opening ( 5 ) at a first end thereof, coaxial to said longitudinal axis and adapted to be connected to a handling station; a movable element ( 3 ) adapted to slide at least partially inside said body; at least one air passage gap provided at a second end of the body or at said first end; wherein the movable element ( 3 ) is adapted to move from a first position, to which a first air passage section corresponds, to a second position, to which a second air passage section corresponds, which is smaller than said first section, so as to adjust a blowing air flow during the cooling step and a suction air flow during the step of retaining the preform.

The invention claimed is: 
     
       1. A cooling and retaining pin for cooling, by means of air blowing, and retaining, by mean of air suction, a preform of plastic material, the pin comprising:
 a body, defining a longitudinal axis and having, at a first end thereof, a first opening, coaxial with respect to said longitudinal axis and adapted to be connected to a handling station; 
 a moveable element adapted to at least partially slide inside said body; 
 at least one gap for a passage of air both during a blowing step and during a suction step, said at least one gap being provided at a second end of the body, opposite to the first end, or at said first end; 
 wherein the movable element is adapted to move from a first position, corresponding to a first section for the passage of air through said at least one gap, to a second position, corresponding to a second section for the passage of air through said at least one gap, said second section being smaller than said first section, so as to adjust in said first position a blowing air flow during the a cooling step and to adjust in said second position a suction air flow during the a step of retaining the preform. 
 
     
     
       2. The cooling and retaining pin according to  claim 1 , wherein the body has a second opening, coaxial to said longitudinal axis, at said second end, wherein said movable element is provided with an internal duct along said longitudinal axis and is adapted to slide from said first position, in which said at least one gap comprises both the internal duct and at least one portion of said second opening for the blowing air flow, to said second position, in which said at least one gap is defined only by said internal duct for the suction air flow. 
     
     
       3. The cooling and retaining pin according to  claim 2 , wherein said second end of the body is provided with a sleeve, integral and coaxial with respect to the body, adapted to delimit therein a stroke of said movable element ( 301 ) from the second position to the first position. 
     
     
       4. The cooling and retaining pin according to  claim 3 , wherein said movable element has a central portion provided with at least one protrusion adapted to slide on an internal surface of said sleeve and to abut, in said first position, at the second opening. 
     
     
       5. The cooling and retaining pin according to  claim 4 , wherein said central portion is provided with three radial protrusions. 
     
     
       6. The cooling and retaining pin according to  claim 4 , wherein said movable element has a first end portion which in said first position projects at least partially from said second opening and has a second end portion, opposite to the first end portion which in said second position is at least partially inserted in an internal duct of the body. 
     
     
       7. The cooling and retaining pin according to  claim 1 , wherein
 the movable element comprises, along said longitudinal axis, a first portion distal from the first opening and a second portion adjacent to said first portion and proximal to the first opening, the first portion having a size larger with respect to the second portion; 
 there is provided only one gap, at said second end of the body, which is comprised between an internal surface of the body and an external surface of the movable element; 
 the movable element is adapted to move so that, when a position of the first portion changes with respect to the body, a size of the gap varies; and 
 wherein, in the first position, the gap is comprised between the internal surface of the body and the external surface of the second portion, and, in the second position, the gap is comprised between the internal surface of the body and the external surface of the first portion. 
 
     
     
       8. The cooling and retaining pin according to  claim 1 , wherein said at least one gap is a single hole or at least two holes, arranged along a circumference coaxial to said longitudinal axis, and wherein the movable element is adapted to move from the first position, corresponding to the first section for the passage of air through said single hole or each hole of said at least two holes, to the second position, corresponding to the second section for the passage of air through said single hole or each hole of said at least two holes. 
     
     
       9. The cooling and retaining pin according to  claim 8 , wherein said single hole or the at least two holes are at the second end of the body, and said single hole or said at least two holes are provided in said movable element arranged at said second end,
 wherein the movable element is in the first position, or advanced position, with said single hole or said at least two holes mainly placed outside the body during a blowing of air from the first opening towards the second end of the body; while the movable element is in the second position, or retracted position, with said single hole or said at least two holes mainly placed inside the body during an aspiration of air from said single hole or from said at least two holes towards the first opening of the body. 
 
     
     
       10. The cooling and retaining pin according to  claim 8 , wherein said single hole or the at least two holes are at said second end of the body, and said single hole or said at least two holes are provided on the second end of the body and the movable element is arranged at said second end, and
 wherein, when the movable element is in the first position, or advanced position, said single hole or said at least two holes have said first section for the passage of air during a blowing of air from the first opening towards the second end of the body; while, when the movable element is in the second position, or retracted position, said single hole or said at least two holes have said second section for the passage of air, smaller than the first section, during an aspiration of air from said single hole or from said at least two holes towards the first opening of the body; and 
 wherein said second end of the body is provided, in a more external position with respect to a position of said single hole or said at least two holes, with a sleeve, integral and coaxial with respect to the body, adapted to delimit a stroke of said movable element from the first position to the second position, and vice versa. 
 
     
     
       11. The cooling and retaining pin according to  claim 8 , wherein said single hole or said at least two holes are at said second end of the body, and said single hole or said at least two holes are provided on the second end of the body and the movable element is arranged at said second end,
 wherein the movable element is provided, in a first stretch thereof, with only one first hole or with at least two first holes having a first size, and provided, in a second stretch thereof, with only one second hole or with at least two second holes having a second size smaller than the first size, 
 wherein the movable element is in the first position, or advanced position, with said only one first hole or said at least two first holes communicating with said single hole or said at least two holes of the body, respectively, during a blowing of air from the first opening towards the second end of the body; while the movable element is in the second position, or retracted position, with said only one second hole or said at least two second holes communicating with said single hole or said at least two holes of the body, respectively, during an aspiration of air from said single hole or from said at least two holes towards the first opening of the body; 
 wherein said second end of the body is internally provided with a sliding bush inside which the movable element can slide, 
 wherein a first end-of-stroke element is integral with the movable element and abuts against an internal shoulder of the body when the movable element is in said first position, and 
 wherein a second end-of-stroke element is integral with the movable element and abuts against said second end of the body when the movable element is in said second position. 
 
     
     
       12. The cooling and retaining pin according to  claim 8 , wherein said single hole or the at least two holes are at said first end, and said single hole or said at least two holes are arranged on the body,
 wherein the movable element closes the first opening in said first end, 
 said movable element being adapted to be arranged in said first position, or retracted position, corresponding to said first section for the passage of air for said single hole or said at least two holes, for a blowing of air from said single hole or from said at least two holes towards the second end of the body, 
 and being adapted to be arranged in said second position, or advanced position, corresponding to said second section for the passage of air for said single hole or said at least two holes, for an aspiration of air from said second end of the body towards said single hole or said at least two holes; and 
 wherein in said second end of the body at least one further hole is provided, arranged along a circumference coaxial to said longitudinal axis. 
 
     
     
       13. A handling station, for handling plastic preforms and adapted to cooperate with an extraction plate adapted to extract the preforms from an injection mold, the handling station comprising a shell defining an internal volume communicating on one side with a plurality of cooling and retaining pins according to  claim 1 , and adapted to communicate on another side with an aeraulic circuit,
 wherein the shell has at least one face provided with said plurality of cooling and retaining pins, 
 wherein the first end of the body of each pin, having the first opening, is arranged inside said shell, and 
 wherein the second end of the body of each pin is arranged outside said shell. 
 
     
     
       14. The handling station according to  claim 13 , wherein in the case where said at least one gap is a single hole or comprises at least two holes at said first end, said single hole or said at least two holes are arranged on the first end of the body along a circumference coaxial to said longitudinal axis, and
 wherein in said internal volume actuation means are provided, adapted to actuate the movable element, which closes the first opening, to pass from the first position, corresponding to a first section for the passage of air through for said single hole or said at least two holes, for a blowing of air from said single hole or from said at least two holes towards the second end of the body, 
 to the second position, corresponding to a second section for the passage of air through for said single hole or said at least two holes, for an aspiration of air from said second end of the body towards said single hole or said at least two holes. 
 
     
     
       15. An apparatus for handling and cooling plastic preforms comprising:
 a handling station according to  claim 13 ; 
 an aeraulic circuit connected to said handling station; 
 wherein said aeraulic circuit comprises:
 a suction duct to aspirate air from the inside of the handling station; 
 a delivery duct to send air to said handling station;
 cooling means arranged along said delivery duct to cool the air sent to said handling station; and 
 
 
 wherein switching means of the aeraulic circuit are further provided, to pass from a first circuit configuration, in which an air passage is possible from the delivery duct to the handling station, to a second circuit configuration, in which an air passage is possible from the handling station to the suction duct, so that air can be blown by means of the plurality of cooling and retaining pins in the first circuit configuration, while air can be aspirated by means of said plurality of cooling and retaining pins in the second circuit configuration. 
 
     
     
       16. An injection molding machine comprising a casing inside which there are at least provided:
 at least one injection mold comprising a plurality of molding cavities; 
 at least one extraction plate comprising at least one set of cooling housings, adapted to receive and retain at least one set of preforms extracted from said molding cavities; said cooling housings being adapted to remove by conduction a first quantity of thermal energy from said preforms; and 
 a handling and cooling apparatus according to  claim 15 , 
 wherein the handling station is configured to pass from a loading position, for cooperating with the extraction plate, to an unloading position for releasing the preforms from said cooling and retaining pins, and 
 wherein, in said loading position, the cooling and retaining pins of the handling station are adapted to cooperate with respective cooling housings of the extraction plate to remove, during a step of blowing air by means of said pins when the aeraulic circuit is in said first circuit configuration, a second amount of thermal energy from said preforms, and then to retain and extract the preforms from said cooling housings during a step of aspirating air through said pins when the aeraulic circuit is in said second circuit configuration. 
 
     
     
       17. A process for handling and cooling plastic preforms in an injection molding machine according to  claim 16 , the process comprising the following steps:
 providing the handling station in the loading position, arranged facing the extraction plate containing at least one set of preforms in the respective cooling housings, and providing the aeraulic circuit in said first circuit configuration; 
 inserting the cooling and retaining pins of the handling station in the respective cooling housings and further cooling the preforms contained in the latter by means of air blowing through said pins having the movable element in the first position; 
 switching the aeraulic circuit, by means of said switching means, from said first circuit configuration to said second circuit configuration and aspirating air through the pins, having the movable element in the second position, to retain the preforms on the handling station; 
 disengaging the cooling and retaining pins from the respective cooling housings continuing to aspirate air through the pins with the movable element in said second position; 
 moving the handling station from said loading position to an unloading position, continuing to aspirate air through the pins with the movable element in said second position; and 
 switching the aeraulic circuit, by means of said switching means, from said second circuit configuration to said first circuit configuration and blowing air through the pins to release the preforms from said pins. 
 
     
     
       18. The cooling and retaining pin according to  claim 9 , wherein said second end of the body is provided with a sleeve, integral and coaxial with respect to the body, adapted to delimit therein a stroke of said movable element from the second position to the first position.